Electric hammer.



A. DE KHOTINSKY.

ELECTRIC HAMMER.

APPLICATION FILED JUNE 10, 1907.

1,140,447. Patented May 25, 1915.

3 SHEETSSHEET l.

A. DE KHOTINSKY.

ELECTRIC HAMMER.

APPLICATION FILED JUNE 10, 1907,

1,140,447. Patented May 25., 1915.

I I1. 3SHEETSSHEET2. 47 y A. DE KHOTINSKY.

ELECTRIC HAMMER. APPLICATION FILED JUNE 10.1907.

1,140,447. Patented May 25, 1915.

3 SHEETSSHEET 3.

M, 65AM viwqc ACHILLES DE KHOTINSKY, OF CHICAGO, ILLINOIS.

ELECTRIC HAMMER.

Specification of Letters Patent.

Patented May 25, 1915.

Application filed June 10. 1907. Serial No. 378,126.

To all 1 7mm. it may] con ern Be it known that I, AcniLLns DE Knorinan Y, a citizen of the United States, residing in Chicago, in the county of Cook and State of Illinois, have invented a n w and useful improvement in Electric Hammers, of which the follmring is a specification.

.ily invention relates primarily to portable electrically actuated hammers, and it has for its primary object the production of an electric hammer of\maximum efficiency and minimum weight and bulk. and for further objects the effecting of all other improve ment in construction and function that are found to btain in the devices hereinafter described or claimed.

in the electric hammer hereinafter set forth. the e is no recoil against the hand of the operator, the retracting stroke of the core being magnetically cushioned: the char' acter and arrangement of the magnetic fields is de igned to avoid overheating of the device. and to this end the magnetic circuits are alanced in such relation as tends to their special ellieieney for the intended work; for increasing the strength of the blow struck. the maximunr magnetic energy is concentrated at the instant of impact of the percussion core: for increasing the frequency of blows. it is sought to make the re iracting action especia ly eliicient and to make the current shift a nd reversal as nearly instantaneous as may be: provision is made f r \:l"".'lll at will the force of the blow; and the entire controlling mechanism is selfcontained within the portable machine-tool itself and is designed to he automatic and meclmni ally positive in action.

In the accompanying; drawings forming a part of this specification. Figure l is a central longitudinal section through the complete device. with the reversing and controlling mechanism shown partly in elention: Fig. 3 is a section on the line 22 of Fig. 1: Fig. 3 is a section on the line 3 3 of Fig. 1: Fig. l is a partial view Sllilllill' to Fig. l but enlarged; Fig. 5 is a section on the line 3 1 of 1; Fig. 6 is a vertical secti n through the current ,diverter, taken on the line (l -ll of Fig. 4': Fig. 7 is a diagrammatic view of the complete electrical circuits and showing the conditions of elec triea. and magnetic euergization as the core approaches, but before it reaches, the limit of its driving stroke; Fig. 8 is a similar diagraimnatic view of the electrical cireuits of the driving electro'magnet, and shows the conditions of electriczl and magnetic energization at the instant when the core begins its driving stroke, and also indicates, by the curve K, K, the acceleration of the core moving under the influence of the progressive augmentation of the magnetic pull drawing the core into the driving coils during the driving stroke; and Fig. 9 is a similar diagrammatic view of the electrical circuits of the retracting electro-magnet. and shows the conditions of electrical and magnetic energization at the instant when the core begins its retracting stroke, and also shows, by the curve L-Ii, the initial acceleration and subsequent retardation of the coremoving under the influence of the progressively diminishing magnetic pull drawing the core into the retracting coils during the retracting stroke, such action constituting the magnetic cushioning of the core at the limit ofits retracting stroke.

Like reference numerals indicate like parts in all of the figures.

10 is the reciprocatory core, of magnetic material, adapted to freely reciprocate Within the core tube 11 and to percussively strike the blow-transmitter 12, which is of magnetic material. The said core-tube is of nonmagnetic material, and is longitudinally slotted, at 13, to prevent magnetic induction, and upon it are wound a series of three successive coils of insulated Wire, 14, 15 and 16. These three coils, of equal length, are all direct-wound, or wound in one direction, and permanently connected end to end with each other. at the loops 17 and 18, by virtue of the fact that they are one continuous uniformly wound wire; so that said three coils are in effect one continuous coil sectionally wound, in three sections, with the permanent connecting loops tapped by the conductors that will be hereafter specilied. Between the adjacent ends of these three coils are the disks of magnetic material 19 and 20, and in contact with the outside periphery of these disks and closely in closing the coils is the casing of magnetic material consisting in the shell 21 and end plate 22. The coils thus inclosed by the magnet-casing and disks, and being thus jacketed both outside and at both ends with magnetic material, constitute, when electrically energized either singly or in series, electro-magnets of the type known as ironclad, which have a maximum efiieieney, in proportion to the amount of wire used, by reason of the shortening of thema etic circuit between the attracted end o the core and the attracting pole of the electro-magnet. The series of coils are electrically energized in pairs, the end coil 14 and middle coil 15 to produce the eflect of retracting the core, and the middle coil 15 and other end coil 16 to produce the eflect of driving the core; and these pairs of coils, thus electrically energized, constitute, in conjunction with the core and their inclosing magnetic casing and disks, two alternately acting electro-magnets, one for retracting and the other for driving the percussion-core. The

retracting magnet includes the electrically energized end coil 14 and middle 'coil 15 and the inductively energized casing 21, end-plate 22 and disk 20,-the disk 19, intermediate the two said coils l4 and 15, being neutral at the instant when the two said coils are fully energized. The driving magnet includes the electrically energized middle coil 15 and other end coil 16, and the inductively energized casing 21, disk 19 and blow-transmitter 12, the disk 20, intermediate the two said coils 15 and 16, being neutral at the instant when the two said coils are fully energized.

The current from one, say the positive, pole of the source of electric energy, which may be the ordinary city power, enters the end coil 16, from the connection 23, at the terminal 24, when the driving fi ld is energized, and, traversing said coil 16, passes over into the middle coil 15, through the loop connection 18, and traversing said middle coil 15 leaves it through the connection 25, tapping loop 17, and thence proceeds to the other or negative pole of the source of energy. YVhen the retracting field is energized, the current from the aforesaid positive pole of the source of energy enters the other end coil 14, the fundamental coil of the retracting magnet, from the connection 26, at the terminal 27, and traversing said coil passes over, through the loop connection 17, into the middle coil 15,.and traversing the latter coil leaves it through the connection 28, tapping loop 18, and thence returns to the negative pole of the source. The aforesaid connection 23, entering the negative terminal of the driving-magnet coils, leads from the positive driving-magnet contact 29; and the connection 25 leads from the positive terminal of the driving-magnet coils to the negative driving-magnet contact 30. The connection 26, entering the negative terminal of the retractingmagnet coils, leads from the positive retractingmagnet contact 31; and the connection 28 leads from the positive terminal of the retracting-magnet coils to the negative retracting-magnet contact 32. The current entering the two aforesaid positive contacts and leaving the aforesaid negative contacts traverses the upper and lower members, respectively, of the two-part oscillating diverter, or contact maker-and-breaker, 33, which is secured to the rock shaft 34 journaled at 35 and 36 in opposed walls of the diverter-box 37. The current from the source of energy enters the one member of said diverter 'from the positive constant contact 38, and leaves the other member of said diverter, to return to the source, through the negative constant contact 39. The connection 40, entering the positive constant contact, leads from the negative side of the spring switch-contact 41, the currentbeing conveyed to the positive side of said spring switch-contact, from the source of energy, by the Wire 42 entering the hole 43 in han dle 44. The current leaving the negative constant contact 39 returns to the source through the wire 45 passing out through the aforesaid hole 43. The plunger 46, operated by means of the thumb-knob 47, makes and breaks the circuit between the poles of the aforesaid switch-contact 41, at the will of the operator.

The positive and negative constant contacts 38 and 39 are located side by side in the same radial position with respect to the center of oscillation of the diverter 33 (see Figs. 4 and 6), and are in constant sliding contact with the broad arms of the righthand and left-hand members (as seen in Figs. 2 and 6), respectively, of the said diverter. The opposed narrow arms of the said members of the said diverter are adapted to make contact with the contacts of the driving-magnet and the contacts of the retracting-magnet in alternation. The said positive and negative driving-magnet contacts, 29 and 30, are side by side in the same radial position, and respectively arranged to make contact with the said right-hand and the said left-hand members, respectively, of the diverter; and the positive and negative retracting-magnet contacts, 31 and 32, are side by side in another radial position, and similarly adapted to make contact with the respective members of the diverter. And the radial or angular separation of the pair of driving-magnet contacts from the pair of retracting-magnet contacts is such that the narrow arms of the diverter-members will a little more than span the space, so that as the diverter oscillates, its contact with the driving-magnet contacts, 29 and 30, is not broken until its contact with the retractingmagnet contacts, 31 and 32, is made, and vice versa; with the result that there is sub stantially no sparking between the diverter and any of the said contacts and the current is substantially constant. The total electrical energization of the coils thus remains substantially constant, While its distribution and direction change. diverter is at one limit of its oscillatory movement, its right-hand member makes the connection between the source of current and the positive driving-magnet contact 29, and its left-hand member makes the connection between the negative driving-magnet contact 30 and the source of energy; and at the other limit of its oscillation, the right-hand member of said diverter makes the connection between the source of energy and the positive retracting-magnet contact 31, and its left-hand member makes the connection between the negative retracting-magnet contact 32 and the source of energy. And when the diverter is in intermediate position, its right-hand member makes connection between the source of energy and the positive contacts of both the driving and the retracting-magnets, and its left-hand member makes connection. from the negative contacts of both the driving and the retracting-mag nets back toward the source of energy.

of the aforesaid'contacts 29, 30, 31, 32, 38 and 39 are quadrilateral carbons freely held in sockets secured in the insulation material forming the opposed walls l8 anti t9 of the diverter-box; and each carbon is constantly pressed outward by a spiral spring Within its socket. The contact-making members of the diverter 33 are surrounded by bushings 50, 50 of insulation material, and this bushing so extended, at 72 (Figs. 2 and 4), on either side of the narrow arms of the*diverter-members as to engage and retain in their sockets the carbons of the contacts released by the said diverter arms at either limit of the diverters oscillation.

1t apparent that the oscillation of the diverter effects the shifting of the electric energization from the driving electro-magnet to the retracting electro-magnet, with the consequent shifting of the magnetic fields influencing the movements of the core; and it is also apparent that the connections between the diy'ertencontacts and the respectively reversed terminals of the two said electro-magnets, are such that as the current shifts from the driving-mag net to the retracting magnet, the direction of the electrical energization will be reversed, thereby effecting the hereinafter considered demagnetization and reversal of polarity of the core and of the blow-transmitter 12.

To automatically oscillate the diverter, by direct mechanical connection with the successive movements of the core, there is provided a stop-rod 51 working freely in an aperture 5'2 extending axially through said core. the said stop-rod being provided with opposed stops 53 and 5t and connected to the middle of the lever 55, the said lever being pivoted at one end to a fixed stud 56. projecting from the inner wall of the di- WVhen the verter-box, and being connected at its other end, by the connecting rod 57, to the diverter itself. \Vithin the stops 53 and 54 respectively are arranged the cushioning stop springs 58 and :39, adapted to engage and be compressed by the respectively opposite ends of the core at or near the limits of its reciprocatory movement. The ends of the core are recessed, at 60 and (31, to accommodate these springs as the core-ends approach the respectively opposed stops; and the blow transmitter 12 is recessed at 02 to accommodate and protect the stop 54 as the percussion-end of the core approaches and strikes the inner face of said blow-transmit ter. As the core approaches the limit of its driving stroke it meets and compresses the corresponding stop-spring 59 until the resistance of said spring overcomes the frictional resistance of and moves the oscillating diverter 33, thereby shifting the electrical energization from the driving magnet into the retracting-magnet and producing the reversal of movement of the core; and as the core approaches the limit of its retracting stroke it engages and compresses the stop-spring 58 until the resistance of said spring overcomes the resistance of and moves the oscillating diverter in the opposite direction, thereby shifting the electrical energization from the retracting into the driving magnet and causing the reversal of the movement of the core to effect the driving stroke.

To carry the diverter as'instantaneously as possible over the interval between the contacts of the driving-magnet and the contacts ot' the retracting-magnet, one end of the diverters rock-shaft 3l has secured to it, at right angles to the axis of the diverter, a crank-arm 63 upon which is looped the spring (ltwhose other end is secured to the stud (55 projecting from the side wall of the diverteubox. As the core strikes either stop-end of the stop-rod 51, the resulting initial movement of said stop-rod stretches, or stores power in. said spring 3i, and then as the member as moves on far enough to release it, this spring, by its sudden retraction, or discharge of its stored power, will act to jerk the said crank'arm ahead and snap the diverter to the other limit of its range of oscillation. This spring-trigger action, snapping the diverter ahead with the spring-power stored by the initial impulse that the core gives the stop-rod, accelerates and insures the oscillatory movement of the diverter. inasmuch as the core is not ellicicntlv attracted in either direction when the diverter is intermediate the contacts of the driving and the relractinganagnets: and except while shifting from one to the other, the diverter is positively and mechanically detained at one or the other of its s'aid contact positions, by reason of the fact that the a the .2 bottom wall of the box. and

crank-arm 63 is thrown over' its center of oscillation and so retained by the spring 64 until the positive movement of the stop-rod by the core shifts said crank-ar'm over to opposite limit of its path of oscillation.

To control the force of the impact or percussion of the core upon. the blow-transmitter, and to gradually increase such force of impact as the operator puts the hammer into action. the entire diverter mechanism, contained in the diverter-box, is made movable to and from the electro-magnets, so that the stop-rod 51, connected to the lever in the diverter-box, may be advanced or receded, through the core, to bring the stop 54 and stop-spring 59 nearer to or farther from the extreme possible limit of the driving stroke of the core. The fart-her the said stop and stop-spring from the said limit, the sooner they are engaged by the percussion-end of the core and the sooner the consequent reversal of the cores movement. If this reversal occurs soon enough, the percussion end of the core will be magnetically cushioned and checked before it reaches or strikes the blow-transmitter, and no blow will be struck. If the reversal is then slightly deferred, the core may reach and lightly strike the blow-transmitter; and as the reversal is still further deferred, the impact of the core upon the blow-transmitter will be increased to its possible maximum. This optional movement of the diverter-box is effected by adapting the lower end of said box to slide on the prolonged upper end of the core-tube 11, and by providing a stud 66 projecting upward from the top of said diverter-box and adapted to be engaged by the middle part of the swinging-lever 67 that is pivoted, at. 68, to the'inner wall of the handle and that carries the thumb-knob and plunger, 47-4G. -The sliding diverter box is radially positioned by the fixed centering-pin passing through a hole in the is normally held retracted position by the spiral spring 70. And the swinging-lever 67 is normally held in its upper or raised position by the spiral spring 71 surrounding the end of stud (36. the operator depresses the thumb-knob 17 the plunger 46 first closes the circuit in the switcl'i-contact and the reciprocatory movement of the core commences, and at the same time the middle of the swinging-lever 67 engages the top of the diverter-box stud 66 and commences the depression of said diverter-box toward the electro magnets.

At first the reversal of the core at the end of its driving stroke may occur before the core meets or strikes the blow-transmitter, and then as the thumb-knob 47 is still further depressed, causing the divcrter-box to be pressed down nearer and nearer to the electro-magnets, the aforesaid reversal of in its outer or the core is more and more retarded so that the blows upon the blow-transmitter become harder and harder and finally reach the maximum when the operator has completely depressed the thumb-knob. Thus this slidable mounting of the diverter-mechanism within the handle casing makes it possible to bring the stroke of the core operatively against the blow-transmitter at any desired point in said stroke, within the limits of such sliding adjustability of the divertermechanism. The large coiled spring normally holds the parts in such relation that the core strikes the blow-transmitter lightly, and as said spring is forcibly compressed it permits the relation of the parts to be so changed that the transmitter is struck harder and harder, the instant of impact of the core, with said transmitter, becoming progressively earlier relatively to the instant of reversal of the cores movement.

The tool-end or blow-transmitter being of magnetic material and all of the parts above the opposite end-plate 22 being of non-magnetic material, the aforesaid retracting magnet becomes of the open iron-clad type, since both ends of the core-tube of said magnet are open, and the aforesaid driving magnet becomes of the stopped iron-clad type, since one end of the core-tube of said magnet is stopped with magnetic material; wherefore the large mass of magnetic material in the blow-transmitter is energized as an attracting pole of the driving magnet, and the magnetic circuit from the percussionend of the core to the attracting pole of the driving electro-magnet is shortened to thestraight distance between the said core-end and the inner or struck face of the blowtransmitter, while the magnetic circuit be tween the other end of the core and the attracting pole of the retracting electromagnet would be represented by a curve from the said core-end to the inner wall of the relatively thin magnetic end-plate 22. As a, result of this distribution of magnetic fields and lines of force, the magnetic attraction between the core and the opposed pole in the stopped end of the driving electromagnet, while the latter is electrically energized, rises to a very abrupt and steeply peaked maximum as the core plunges toward the blow-transmitter 12, producing the acceleration of movement diagramn'latically indicated by the curve 70 in Fig. 8, so that the impelling force is concentrated close to the point of impact; while the magnetic attraction between the core and the opposed or attracting poles of the retracting electro-magnet, while the latter is electrically energized, is initially accelerated to a maximum and gradually falls off to zero as the core approaches and reaches the end-plate 22, producing the initial acceleration and sequent retardation of movement diagram matica ly indicated by the curve L in Fig. so that the retracting force is distributed in gradually diminishing measure and the core is magnetically cushioned Within its retracting stroke and does not tend to have its upper end thrown above the aforesaid end-plate ln this manner there is attained the maximum efliciency of blow upon the tool-cnd or blow-transmitter 12, and yet no back stroke or consequent recoil is produced in the retracting of the core after each working blow struck. The general principle that controls the increased effectiveness. for their respective purposes, of the open" and stopped iron-clad magnets above described, is twofold. First:that the shorter the air gap or circuit between the attracted end of the core and the attracting end of the electro-magnet, the greater 3 the number of lines of magnetic force there will be within the length of the said aircircuit. and the greater the consequent, intensitv of the magnetic attraction; and this applies equally to the relation between the other end of the core and the corresponding opposite pole of the active magnet during the retracting action and the driving action respectivelyr that is to say, during the driving action, the magnetic circuit from the upper part of the core to the upper pole of the driving magnet is shortened to the distance from such part or" the core to the inner wall of the magneticdisk l9,whileduring the retracting action. the magnetic circuit from tin lover cnd ot the core to the lower pole of the r tra ting electro-magnet is shortrncd to th distance between the said part of the cor andthe inner wall of the magnetic disk :flr. fiecon im that the mass it: of magn tic material in thrmagnetic stop per" the ,doppcd iron-clad magnet conccntratcs th lines ol magnetic force near said aopped end of th driving magnet: wh le th unilo 'n magn tic jacket of the open retracting mag distribute such llllt:-. 1i; gradual; decrcavg concentration along: the \v' 'aiwgap time the core to the rrt rwt'tou rial ol Shel agnet, the disl; pul i ving the re v abruptly tron-t a maximum. when H l c r Ll'lliim nc l)l \\'-it'. anitter l2: but the toa: jneti:- n'l retracting; the core van- 'j 'ltllitlll in the cote :lPPlUtHl'it and a the did. :L. o iron. the tortgoing. it iYlOllr. that th iie ii' o5 Lhe rt Hi -ting iit2-l ii and the iir orb mg magnet. w-pectivehJ indzopen ' wed on i 'll tncr. hwause.

i it i. encag duriaction ard the end i :ving :n 1 Will the it mtll ant is elernoaction both. of the ieng h nclgllictl during tli coil 13;, t innior tiie v rncl'g'i ml. durin; Ant the core i subs axially t of two of the coils, so that at the end of its driving stroke it just completes the magnetic aXis of the driving magnet, and at the end of its retracting stroke it becomes and just equals the substantially-balanced magnetic axis of the retracting magnet. The equality of the two end coils with each other, and of each with the middle coil, in the magnets having thus superposed fields, permits the utilization, in each stroke, of the maximum possible proportion, two-thirds, 0* the total possible efiiciency of the entire of three coils, and at the same time permits each of the end coils to be used at its own highest possible efliciency, as limited by the winding, without super-heating either, as each otters the same resistance to the same current. The abo e-described partial coinci deuce orv mutual superposition of the fields of the two magnets upon each other effects the greatest possible compactness of construction and saving of weight and material because of the two-told utilization of the one middle coil 15 and also by reason of the fact that the magnetic disks l9 and 20. which are alternately neutral when occupying the positions intermediate the energized coils, become in alternation the like magnetic poles of the alternately and reversely energized electroanagnets and make each of said magnets completely and uniformly ironclad. The partial superposition of the two magnetic fields, by making the middle coil common to hoth the retracting and the dr ing magnets. and the reversal of the current for the retracting action. further etlects the demagnetization of the blowtransmitter 12, and reversal of the polarity of the core. at the end of the driving stroke. As the core i of hardened magnetic material. preferahlv steel. it becomes polarized during each s! roke. and at the end of the driving stroke would tend to remain permanently attracted and held to the struck face of the blow-transmitter 1;. "the demagnetization necessary t prewnt this holding or sti king of the re is ell'ecied by rev *rsing the direction oi th electrical energization or current as the 'ilti energi/ation is shifted from the drivmg magnet into the retracting magnet. so that the p arity of the core ant til the magucceasing oi the coils will he iverscd. net:- ilizing the residual polarity ot the bimvnsmitt-a that constitutes the magnetic Ripp r the topped end of the, -rtclai ngn wnet and inducing some llO The demagnetization and reversal of polarit Y of the core, slightly before the reversal of polarity of the blowtransmitter, of course produces an instant repulsion between the blow-transmitter and the adjacent end of the percussion core, thereby permitting said core to be retracted by, or even repelling it toward, the field of the retracting magnet. By reason of this reversal of the direction of the electrical energization, it is obvious that while the current will always be in one direction in the end coil 16, the fundamental coil of the driving magnet, and will always be in the opposite direction in the other end coil 14, the fundamental coil of the retracting magnet, it will be alternately first in the one direction and then in the other in the middle coil -15, when the electric energization fully occupies first the driving field and then the retracting field respectively, and will be substantially neutral in said middle coil 15, for an instant intermediate the two limits of the shifting of the energization from the one field to the other. During this last mentioned instant of neutral condition in the middle coil the magnetic influence acting upon the core will be transferred from one to the other of the ad coils 14: and 16, and as soon as the electric energization of the middle coil is actually reversed in direction, said middle coil, always inclosing a half part of the core 10, will directly exert its influence upon said core to further the required demagnetization and reversal of polarity thereof. And the aforesaid superposition of the retracting and the driving magnetic fields, has a still further function in facilitating the use of a substantially constant uninterrupted electrical current, gradually, instead of abruptly, shifted from the one field of energization into the other-without substantial break or interruption in the magnetic control of the core, there being a progressive reduction of electric current in the end coil J6 the electric energization shifts into the retracting field, and, vice versa, a gradual reduction of electric current in the other end coil 14 as the electric energization shifts into the driving field, as more fully appears in the foregoing description of the connections between the source of current and the series of coils.

longer than the core.

My invention is hereinabove set forth as v embodied in a particular form of construction, but I do not limit it thereto or to less than all the possible forms in which the said invention as hereinafter claimed may be embodied prior devices for I claim 1. In an electric hammer, in combination: a reciprocatory magnetic percussion-core Within, and itself about two-thirds the like purposes.

' length of, three axially alined and contigu' and distinguished from ous equal coils adapted to be alternately energized in series in pairs; a peripheral, end and intermediate jacketing of magnetic material, constituting said coils ironclad; connections of one polarity leadin LO the free ends of the end coils, and or opposite polarity tapping the connections between the middle and end coils, whereby the coilsmay be energized in pairs to produce in alternation a driving and a retracting motormagnet of reverse polarity and having a half-part of their fields superposed; a blowtransmitter of magnetic material at the impact end of the driving magnet, constituting said magnet of stopped type, the retracting magnet being of open type; automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being mechanically controlled by the reciprocating core and having an oscillating diverter adapted to be shifted to the alternately active contacts and to span the space between them, and a stop-rod cooperating with said diverter and freely inserted longitudinally through the core and provided with opposed stops and with opposed cushioning means to cushion the movement of said stop-rod, and a spring-trigger mechanism for snapshifting the diverter and for detaining the diverter at either limit of its throw; and optionally operable means for graduating the impact of the 'core upon the blow-transmitter, said means including a slidably movable member, for approXi mately the point of impact and the diverter mechanism, and a coil spring normally holding the parts in such relation as to give the lighter impact but compressibly yielding to permit heavier impact; substantially as 2. In an electric hammer, in combination: a reeiprocatory magnetic percussion core reciprooating within, and itself about twothirds the length of, three axially alined and contiguous equal coils adapted to be alternately energized in series in pairs; and connections whereby the coils may be energized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the successive positions thereof substantially as specified.

3. In an electric hammer, in combination: a reciprocatory magnetic percussion-core reciprocating within three axially aiincd and contiguous coils adapted to be alternately energized in series in pairs; and comiections of one polarity leading to the free ends of the end coils, and of opposite polarity tapping the connections between the middle and end coils, whereby the coils may be ener gized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the successive positions there of: substantially as specified.

t. In an electric hammer, in combination: a reciprocatory magnetic percussion-core reciprocating within three axially alined and contiguous coils adapted to be alternately energized in series in pairs; and connections of one polarity leading to the free ends of the end coils, and of opposite polarity tapping the connections between the middle and end coils, whereby the coils may be energized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; substantially as specified.

In an electric hammer, tion: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils adapted to be alternately energized in series in groups; and connec-' tions whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a half part of their fields superposed in respect to the successive positions thereof; substantially as specified.

l2. In an electric hammer, in combination: a rm'iprocatorv magnetic percussion-core reciprocating within axially alined and contiorious c ils adapted to he alternately enered in series in group and connections whereby the coils may he energized to pro duce in alternation a driving and a retract ing motor-magnet of respectively completely re erse polarity and having a part of their fields superposed in respect to the succi-ssiie positions ther of; substantially as :ipa'cified.

7. in an electric hammer, in combination: a rceiproculory magnetic percussion-core recipr ating within. and itself about two- =lthe length of. three axially alined and .rontiguou; gignal coils: a periphera nd and ii tcrmedia; iarkeliug' l' magneth iiaterial tornxiitiitisar all oi aid; coils ironclad; and =o-n tions zvherel x the oils may be ener n r to 172;" in alternation a motor-magnet o? xi xn'ity an! in; c; a no: 1.. zpcrpo wi i. ['l 'e pwiiions than oi ubs LIEillfI as s t tied cries n airs; a wriphei ii. ncdiatri dieting oi magn t n titutina mid coil ironclv-ui eonnetiions Win-r 1 the. rich; may n in combinaenergized to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; substantially as specified.

9. In an electric hammer. in combination: a reciprocatory magnetic percussion-core reciprocating within three axially alined and contiguous coils; a peripheral, end and in termediate jackcting of magnetic material, constituting all of said coils ironclad; connections whereby the coils may be energized in pairs to produce in a ternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a halt part it their fie ds superposed in respect to he successive positions thereof: and a hlow-transmitter of magnetic material at the impact end 0." the driving magnet, constituting said magnet of stopped type, the retracting magnet being of open type; substantially as specified.

10. In an electric hammei: in combination: a reciproeatory magnetic percussioncore re iprocating \vithin axially alined and contiguous coils: a jacketing of magnetic materiah constituting all of said coils ironclad; connection whereby the coils may he energized to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive po itions thereof; and a blow-transinitter of magnetic material at the impact end of the dri\ing magnet. cons. tutiiig said magnet of stopped type. the retra tii'ig magnet being? of open type; substaiuially as specified.

ll. In an electric hammer. in combination; a reciprocatory magnetic pll'tlw oncore reciprocating within. and itself about two-thirds the length ol'. ihi axially alined and contiguous equal coils adapted to h alternately energized in se in pairu a p ripheral, end and intern'iwlnit iaclo magnetic material. eon & :ting sa ironclad: connections oi" om daril l to the fr e ends of the tin: ils. ai: l ti n posilc polarity tappirg tie onnection tween th iniddh :znd end i t. whor -h coils Znfl' be My d in pas to pi dinc if alternation a and a z'etrartinii luili l jl ii the 7 ill lU-Li llt) alternately energized in series in pairs; a peripheral end and intermediate jacketing of magnetic material, constituting said coils ironclad; connections of one polarity leading to the freeends of the end coils, and of opposite polarity tapping the connections between the middle nd end coils, whereby the coils may be eneigized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; and a blow-transmitter of magnetic material at the impact end of the driving-magnet, constituting said magnet of stopped type, the retracting magnet being of open type; substantially as specified.

13. In an electric hammer, in combination: a reciprocatory magnetic percussion- -core reciprocating within three axially i of the end coils,

alined and contiguous coils adapted to be alternately energized in series in pairs; connections of one polarity leading to the free ends of the end coils, and of opposite polarity. tapping the connections between the middle and end coils, whereby the coils may be energized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the successive positions thereof; and diverter-mechanism for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core; substantially as specified.

14. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within three axially alined and contiguous coils adapted to be alternately energized in series in pairs; connections of one polarity leading to the free ends and of opposite polarity tapping the connections between the middle and end coils, whereby the soils may be energized in pairs to produce in alternation a driving and a retracting motor-magnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the successive positions thereof; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being controlled by the re cip'rocating core; substantially as specified.

15. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motormagnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core; substantially as specified.

16. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motormagnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; and automatic diverter-mechanism, self-contained in the device, for di verting the current alternately from one field to the other, said mechanism being mechanically controlled ing core; substantially as specified.

17. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating Within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motormagnet of respectively completely reverse polarity and having a part of their fields superposed in respect to the successive positions thereof; and automatic di"erter-mech anism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being mechanically controlled by the reciprocating core and having an oscillating diverter adapted to be shifted to the tive contacts; substantially as specified.

18. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within three axially alined and contiguous equal coils adapted to be alternately energized in series in pairs; connections of one polarity leading to the free ends of the end coils, and of opposite polarity tapping the connections between the middle and end coils, whereby the coils may be energized in pairs to produce in alternation a driving and a retracting motormagnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the succes sive positions thereof; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being mechanically controlled rocating core and having an oscillating diverter adapted to be shifted to the alternately active contacts; substantially as specified.

19. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within three axially alined and contiguous coils; a jacketing of magnetic material, constituting all of said by the reciprocatalternately acby the recipcoils lIOIlQitlCl; connections whereby the coils may be energized in pairs to produce in al- I ternation a driving and a retracting motormagnet of respectively completely reverse polarity and having a half-part of their fields superposed in respect to the successive positions thereof; a blow-transmitter of magnetic material at the impact end of the driving magnet, constituting said magnet of stopped type, the retracting magnet being of open type; and automatic divertermechanism, self-contained in the device, for diverting the current alternately from one field to the other; substantially as specified.

20. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils; a jacketing of magnetic material, constituting said coil ironclad; connections, insulated from the core, Wl18I6 by the coils may be energized to produce in alternation a driving and a retracting motor-magnet, respectively fully energized instantly upon each reversal; a blow-transmitter of magnetic material at the impact end of the driving magnet, constituting said magnet of stopped type adapted to augment the impact of the core, the retracting magnet being of open type adapted to check the retraction-s roke of the core; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being mechanically controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts extraneous to said core; substantially as specified.

21. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within three axially alined and contiguous coils adapted to be alternately energized in series in pairs; connections of one polarity leading to the free ends of the end coils, and of opposite polarity tapping the connections between the middle and end coils, whereby the coils may be energized in pairs to produce in alternation a driving and a retracting motor-magnet of reverse polarity and having a halfpart of their fields superposed in respect to the successive positions thereof; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from me field to the other, said mechanism being controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts and to span the space between them; substantially as specified.

22. In an electric hammer, in combina-' tion: a reciprocatory magnetic percussioneore reciprocating Within axially alined and contiguous coils; connections whereby the coils may he energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one magnet field to the other, said mechanism being mechanically controlled by the reciprocating core and having an oscillating diverter adapted to be shifted to the alternately active contacts, and a stop-rod cooperating with said diverter and the core", substantially as specified.

23. In an electric hammer, in combination: a i ciprocatory magnetic percussioneore reciprocating Within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one magnet field to the other, said mechanism being mechanically controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a stop-rod cooperating with said diverter and freely inserted longitudinally through he core and provided with opposed stops; substantially as specified.

2 1. In an electric hammer in combination: a reciprocatory magnetic percussioncore reciprocating \vithin axially alined and contiguous coils; conn ctions whereby th'icoils may be energized to produce in alternation a driving and a retracting motormagne and automatic diverter-mcchanism, selfcontained in the device, for diverting the current alternately from one ma gnet field to the other. said mechanism being mechanically controlled by the reciprocating core and having an oscillating diverter adapted to be shifted to the alternately active eontaets, and a'stop-rod coacting with saio d1 vcrter and the core and provid d with op posed cushioning means to cushion the movement of said stop rod", substantiall as specified.

25. In an electric hammer, in combination: a, reciprocatory magnetic percussion core reciprocating \viihin axially alined and eontiguous coils; connections 'vvheieby the coils maybe energized to produce in alternation a driving and a ret acting motor-inagnet; and automatic diverter-mechanir-1n, sell-conta ned in the device, for diverting the current alternately from one magnet iieid to the other. said mechanism benrif mechanically controlled by the l6Cl} ,"l t':l't1llI core and having a diverter adapted to H0 shifted to the alternately active contacts, and a stop rod cooperating v ith said diverter and freely inserted longitudinally through the core and provided with opposed stops and with opposed cushioning means to eusliioiz the movement of said stoprod; bstantiaii specified.

26. In an electric hammer, in combination: a reciprocatory magnetic percussioncore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a drivautomatic diverter mechanism, self contained in the device, for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a spring-trigger mechanism for snap-shifting the diverter and for detaining the diverter at either limit of its throw; substantially as specified.

27. In an electric hammer, in combination: a reciprocatory magnetic percussioncore within axially alinedi and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a spring-trigger mechanism for snapshifting the diverter; substantially as specified.-

28. In an electric hammer, in combination: a reciprocatory magnetic percussioncore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter mechanism, self contained in the device for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a springtrigger mechanism for detaining the diverter at either limit of its throw; substantially as specified.

29. In an electric hammerjdn combination: a reciprocatory magnetic percussioncore within axially alined and contiguous co s; connections \vl'iereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said mechanism being controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a mechanism for snap-shifting the diverter and for detaining the diverter at either limit of its throw; substantially as specified.

30. In an electric hammer, in combination: a reciprocatory magnetic percussionmg and a retracting motor-magnet; andcore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting thecurrent alternately from one field to the other, said mechanism being mechanically controlled by the reciprocating'core and having a diverter adapted to be shifted to the alternately active contacts, and a stop-rod cooperating with said diverter and the core and provided With opposed cushioning means to cushion the movement of said stoprod, and a mechanism for snap-shifting the diverter and for detaining the diverter at either limitof its throw; substantially as specified.

31. In an electric hammer, in combination: a reciprocatory magnetic percussioncore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a -driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for'diverting the current alterfnately from one field to the other, said mechanism being mechanically controlled by the reciprocating core and having a diverter adapted to be shifted to the alternately active contacts, and a stop-rod cooperating with said diverter and freely inserted longitudinally through the core and provided with opposed stops and with opposed cushioning means to cushion the movement of said stop-rod, and a mechanism for snapshifting the diverter diverter at either limit of its throw; substantially as specified.

32. In an electric hammer. in combination: a reciprocatory magnetic percussioncore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a'driving and a retracting motor-magnet; and automatic diverter-mechanism. self-contained in the device, for diverting the current alternately from on field to the other, said mech anism being mechanically controlled by the reciprocating core andha ving an oscillating diverter adapted to be shifted to the alternately active contacts, and a spring-trigger mechanism for snapshifting the diverter and for detaining the diverter at either limit of its throw; substantially as specified.

33. In an electric hammer, in combination: a reciprocatory magnetic percussioncore within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current aland for detaining thei nately from one field to the other, said mechanism being mechanically controlled by the reciprocating core and having an oscillating diverter adapted to be shifted to the alternately active contacts, and a stop rod cooperating with said diverter and freely inserted longitudinally through the core and provided with opposed stops and with opposed cushioning means to cushion the movement of said stop-rod, and a mechanism for snap-shifting the diverter and for detaining the diverter at either limit of its throw; substantially as specified.

34. In an electric hammer, in combination: a 'reciprocatory magnetic percussion core within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alternation a driving and a retracting motor-magnet; and automatic diverter-mechanism, self-contained in the device, for diverting the current alternately from one field to the other, said meclanism being mechanically controlled by ti, 1 reciprocating core and having an oscillating diverter adapted to be shifted to the alternately active contacts, and a stop-rod cooperating with said diverter and the core and provided with opposed cushioning means to cushion the movement of said stop-rod, and a spring-trigger mechanism fo snapshifting the diverter and for detaining the diverter at either limit of its throw; sub' stantially as specified.

35. In an electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils; connections whereby the coils may be energized to produce in alters nation a driving and a retractingmotormagnet; automatic divertcr-mcchanism, selfcontained in the device, for diverting the current alternately from one magnet to the other, said mechanism being mechanically controlled by the reciprocating core and having a. diverter adapted to be shifted to the alte natively active contacts; and prissiiiccmitrollecl means, actuated by the mere 'ng of the hammer to its Work, for grad uatinsz the impact of the core upon the bloiv transmit er; substantially as s ecified.

b. in an electric hammer, in comoinzr tion: reciprocatory magnetic percuss mneating Within axiallv 'incd and coils; conne iions w may be energized to produce nation a driving and a retracting motor magnet: automatic diverter-mechanism. selfcontained in the device, for diverting the ent alternately from one magnet to the ii-er, said mechanism being mecl'ianically controlled by the reciprocating core and having a diver-{pr adapted to be shitted to alternately active contacts; and optionoperabli pressure-controlled means actuated by the mere pressing of the hammer to its work, for graduating the impact of the core upon the blow-transmitter; substantially as specified 37. In a1. electric hammer, in combination: a reciprocatory magnetic percussioncore reciprocating within axially alined and contiguous coils; connections whereby the coils may be ener iz-cd to produce in alternation a driving and a retracting motor-magnet; automatic diverter-mechanism, selfcontained in the device, for diverting the current alternately from one magnet to the other, said mechanism being mechanically controlled by the reciprocating core and having a di crter adapted to be shifted to the alternately active contacts; and-optionally operable pressurecontrolled means, actuated by the more pressing of the hammer to its' work, for graduating the impact of the core upon the blow-transmitter, said means including a slidably movable member, for approximating the point of impa t and the dicontrolled by the reciprocating corerand having a diver-tor adapted to-bc shifted to the alto natcly active contacts; and optionally operable pressure-controlled means, actnited by the mere pressing of the bum mer to its work, for graduating bile impact of the core upon the blow-transmitter, said means including a slidably movable member and -a coil ring normally holding the lation as to give the lighter ucssiblv yielding to permit l/Zllltllllh as specified.

hammer, in combinamagrwtic percussion Thin axially alined and icctions whereby the coils may l l to produce in alternation a drill :d a retracting motormagnei: automa, divcrtercncchanism selfcont-aiicd in the drvire, for diverting the current alternately from one, magnet to the other aid mechanism being mechanically control ed by the reciprocating core and 39. In an tion: a rccr core lrocati contiguoir; co

havinc a divcrtcr adapted to be shifted to the a .ernatcly active contact: and optionot er ale pressure-controlled means,

actuated by the mere pressing of the harhyielding to permit heavier impaet; substanmer to its work, for graduating the impact tially as specified.

of the core upon the blow-transmitter, said ACHILLES DE KHOTINSKY. means including a movable member and a Witnesses: spring normally holding the parts in such HENRY Lovn CLARKE,

relation as to give the lighter impact but WILLIAM A; GEIGER. 

